DIN 40NiCrMo2-2 Alloy Steel Bar 40NiCrMo2-2 Round Bars & Rod

Product Description

DIN 40NiCrMo2-2 (Material Number 1.6546) is a medium-carbon, nickel-chromium-molybdenum "triple-alloy" through-hardening (quench and temper) structural steel.

Unlike low-carbon case-hardening grades (like 20NiCrMo2-2 / AISI 8620), 40NiCrMo2-2 contains higher carbon (~0.40%), allowing it to achieve exceptionally uniform high strength, wear resistance, and deep hardenability throughout its entire cross-section. It is highly valued as a cold-heading or hot-rolled grade for high-fatigue fasteners and heavily loaded machinery parts.

Technical Specifications & Global Equivalents

40NiCrMo2-2 aligns directly with the widely utilized American AISI 8740 chemistry. When cross-referencing materials globally, the equivalents include:

Chemical Composition (DIN 1.6546 / EN 10263-3)

The balancing of nickel, chromium, and molybdenum prevents grain coarsening during high-temperature treatments and ensures minimal distortion when oil quenched.

• Carbon (C): 0.37% 0.44% (allows high base hardness without case-carburizing)

• Nickel (Ni): 0.40% 0.70% (imparts structural core toughness and impact strength)

• Chromium (Cr): 0.40% 0.60% (increases wear resistance and depth of hardenable zone)

• Molybdenum (Mo): 0.15% 0.30% (prevents temper brittleness)

• Manganese (Mn): 0.70% 1.00%

• Silicon (Si): 0.15% 0.40%

• Phosphorus (P): max. 0.035%

• Sulfur (S): max. 0.035%

Key Mechanical Properties & Processing

• Supply Condition: Typically supplied as hot-rolled or cold-drawn round bars in the Spheroidize Annealed (+AC) or Treated for Cold Shearability (+S) state to accommodate cold-upsetting or heavy machining before final hardening.

• Quenched & Tempered (Q+T) Strength: Typically targeted for a final tensile strength of 9001200 MPa, depending on the tempering temperature.

• Cold-Forming Response: As a specification under cold-heading standards, it exhibits excellent cold workability with relatively low-to-medium work-hardening rates.

Core Engineering Applications

Because 40NiCrMo2-2 round bars offer excellent torque resistance and high fatigue strength under cyclic loads, they are extensively chosen for:

• High-Strength Fasteners: Heavy-duty engine bolts, aircraft-grade fasteners, socket head caps, and connecting rod bolts.

• Drivetrain Components: High-fatigue axles, power-transmission shafts, crankshafts, and torsion bars.

• Industrial Hardware: High-tensile clamping components, steering linkages, and critical wear rods in mechanical presses.